'The Succession in Great Britain, Showing the Union of the Crowns', late 20th century. Family tree showing the various royal houses and illustrating the Union of the Crowns which was the accession of James VI of Scotland to the thrones of England and Ireland, and the consequential unification of the three realms under a single monarch in 1603. The Union of Crowns followed the death of Queen Elizabeth I of England (1533-1603), the last monarch of the Tudor dynasty, who was James's unmarried and childless first cousin twice removed.